Efficient shortest path search in large road network environment: A heuristic approach

The road network now opens a new application area for the classic k-nearestneighbors (k-NN) queries, which retrieve k objects closest to a given query point. However, since most existing schemes are built on top of the Euclidean distance, they just find the k objects, failing in discovering the shortest paths to them and thus possibly bringing the so-called false dismissal problem. Aiming at finding both k objects and the shortest paths at the same time, this paper first selects candidate objects by the k-NN search scheme according to the underlying index structure and then finds the path to each of them by the modified A* algorithm. The path finding step stores the intermediary paths from the query point to all of the scanned nodes and then attempts to match the path segment common between the stored paths and the path to a new scan node instead of repeatedly running A* algorithm for each k point. Experiment results show that, for the road network data of Oldenburg Road Network and California Road Network, the proposed scheme improves the search speed by 1.3-3.0 times, compared with incremental network expansion, post-Dijkstra, and naive method, also reducing the number of scan nodes by 11.8-66.8 %.